1. Field
The application relates to an article comprising at least one magnetocalorically active phase and methods of working an article comprising at least one magnetocalorically active phase.
2. Description of Related Art
The magnetocaloric effect describes the adiabatic conversion of a magnetically induced entropy change to the evolution or absorption of heat. By applying a magnetic field to a magnetocalorically active material, an entropy change can be induced which results in the evolution or absorption of heat. This effect can be harnessed to provide refrigeration and/or heating.
Magnetic heat exchangers, such as that disclosed in U.S. Pat. No. 6,676,772, typically include a pumped recirculation system, a heat exchange medium such as a fluid coolant, a chamber packed with particles of a magnetic refrigerant working material which displays the magnetocaloric effect and a means for applying a magnetic field to the chamber.
Magnetic heat exchangers are, in principle, more energy efficient than gas compression/expansion cycle systems. They are also considered environmentally friendly as chemicals such as chlorofluorocarbons (CFC) which are thought to contribute to the depletion of ozone levels are not used.
In recent years, materials such as La(Fe1-aSia)13, Gd5(Si,Ge)4, Mn(As,Sb) and MnFe(P, As) have been developed which have a Curie temperature, Tc, at or near room temperature. The Curie temperature translates to the operating temperature of the material in a magnetic heat exchange system. These materials are, therefore, suitable candidates for use in applications such as building climate control, domestic and industrial refrigerators and freezers as well as automotive climate control.
Consequently, magnetic heat exchanger systems are being developed in order to practically realise the advantages provided by the newly developed magnetocalorically active materials. However, further improvements are desirable to enable a more extensive application of magnetic heat exchange technology.